Design of Speed Regulator for Four Quadrant Operation with Derating and Delay

This paper presents the design of a speed regulator for an interior permanent magnet synchronous motor (IPMSM) in traction unit applications. The regulator functions as the outer loop of a cascaded control system, with the torque control loop implemented through look-up table (LUT)-based vector control specifically field oriented control (FOC). The derating of the LUT due to safety functionalities as well as the computational delay of the digital signal processor (DSP) are taken into consideration in real-time scenario. The electrical and mechanical parameters of the IPMSM are estimated following IEEE Std 1812 guidelines, ensuring accurate computation of the controller gains. Despite challenges posed by non-ideal hardware factors, such as voltage source inverter (VSI) nonlinearities and parameter saturation, simulation and hardware-in-the-loop (HIL) results demonstrate that the designed speed regulator effectively tracks its reference under four-quadrant operation. These findings validate the suitability of the proposed regulator for traction applications.